Production of thin film electronic devices has developed over the years towards increasingly cost-efficient large-scale production. For mass fabrication of semiconductor devices such as organic light emitting diodes (OLEDs), electrochrome devices and photovoltaic devices, a very interesting technology is roll-to-roll processing, in which the device is built on a flexible, possibly transparent, substrate material such as a plastic sheet.
A substrate sheet to be used in mass production of e.g. OLEDs may be formed on a sacrificial metal substrate on which a metallic shunting structure and a barrier layer are applied and optionally laminated or covered with an organic coating to produce a sheet. Next, the sacrificial metal substrate is etched away to leave a self-supporting flexible substrate sheet having barrier properties and a shunting structure. A semiconductor device may then be built on the surface of the sheet which faced the sacrificial metal substrate before its removal.
However, the approach described above suffers from several disadvantages. First, aluminum sheet, which is commonly used as the sacrificial metal substrate, has a surface roughness which causes the resulting substrate sheet to have poor barrier qualities when a semiconductor device is produced thereon, thus limiting its use to fabrication of devices which do not require a high quality barrier. Furthermore, etching the metal substrate is time consuming, thus providing an obstacle to achieving more time- and cost-efficient fabrication processes.
Thus, there remains a need in the art for improved methods for low-cost mass production of thin film semiconductor devices.